The human digestive system uses a series of enzymes to break down complex foods into simple molecules (e.g., sugars, peptides and lipids) that can be absorbed by the body. The inability or diminished capacity of the body's production of one or more enzymes that are crucial for proper digestion can lead to gastrointestinal symptoms that have been characterized by the medical community as irritable bowel syndrome (IBS). A patient with IBS typically presents clinically with one of three variants: i) chronic abdominal pain and constipation (also known as spastic colitis); ii) chronic intermittent diarrhea, often without pain; or iii) both features, in an alternating cycle of constipation and diarrhea.